Updates the fat_fs sample documentation to reflect that it can run on
multiple boards, not just the nrf52840_blip.
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>
Name all subsystem reference consistently with an '_api' postfix and
clean up naming and folder structure in some cases.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>